[PATCH 1/1] tools headers: Sync uapi/linux/prctl.h with the kernel source

[Arnaldo Carvalho de Melo]

tldr; Just FYI, I'm carrying this on the perf tools tree.

Full explanation:

There used to be no copies, with tools/ code using kernel headers
directly. From time to time tools/perf/ broke due to legitimate kernel
hacking. At some point Linus complained about such direct usage. Then we
adopted the current model.

See further details at:

 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/include/uapi/README

To pick up the changes in these csets:

  8cdc4d27019356b0 ("mm/huge_memory: respect MADV_COLLAPSE with PR_THP_DISABLE_EXCEPT_ADVISED")
  9dc21bbd62edeae6 ("prctl: extend PR_SET_THP_DISABLE to optionally exclude VM_HUGEPAGE")

That don't introduce anything of interest for the tools/, just
addressing these perf build warnings:

  Warning: Kernel ABI header differences:
    diff -u tools/perf/trace/beauty/include/uapi/linux/prctl.h include/uapi/linux/prctl.h

Please see tools/include/uapi/README for further details.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/trace/beauty/include/uapi/linux/prctl.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/trace/beauty/include/uapi/linux/prctl.h b/tools/perf/trace/beauty/include/uapi/linux/prctl.h
index ed3aed264aeb2881..51c4e8c82b1e9889 100644
--- a/tools/perf/trace/beauty/include/uapi/linux/prctl.h
+++ b/tools/perf/trace/beauty/include/uapi/linux/prctl.h
@@ -177,7 +177,17 @@ struct prctl_mm_map {
 
 #define PR_GET_TID_ADDRESS	40
 
+/*
+ * Flags for PR_SET_THP_DISABLE are only applicable when disabling. Bit 0
+ * is reserved, so PR_GET_THP_DISABLE can return "1 | flags", to effectively
+ * return "1" when no flags were specified for PR_SET_THP_DISABLE.
+ */
 #define PR_SET_THP_DISABLE	41
+/*
+ * Don't disable THPs when explicitly advised (e.g., MADV_HUGEPAGE /
+ * VM_HUGEPAGE, MADV_COLLAPSE).
+ */
+# define PR_THP_DISABLE_EXCEPT_ADVISED	(1 << 1)
 #define PR_GET_THP_DISABLE	42
 
 /*
-- 
2.51.0